Fetal to Newborn Transitions Flashcards
Which lobe of the liver has a higher oxygen concentration in utero?
The left lobe, because it receives its blood supply exclusively from the well oxygenated umbilical vein. The right lobe is supplied by a mixture of well oxygenated umbilical venous blood and poorly oxygenated portal venous blood.
When does the ductus venosus close after birth?
The ductus venosus anatomically closes 3-7 days after birth.
What factors can lead to persistent pulmonary hypertension of the newborn?
Factors which cause neonatal distress, such as: hypothermia, acidosis, hypoxia, and/or hypercapnia.
At birth, what happens to the pulmonary vascular resistance?
At birth, pulmonary vascular resistance decreases significantly in response to ventilation and resultant lung expansion.
At birth, what happens to the pulmonary blood flow?
At birth, the pulmonary blood flow increases significantly due to the decrease in pulmonary vascular resistance.
At birth, what happens to the mean pulmonary artery pressure?
At birth, the mean pulmonary artery pressure drops dramatically.
What normally happens with the foramen ovale after birth?
After birth, the left atrial pressure rises while the right atrial pressure falls, leading to closure of the foramen ovale.
What is the usual time course for closure of the ductus arteriosus after birth?
The ductus constricts rapidly after birth in response to falling levels of prostaglandin and increased levels of oxygen. It is usually functionally closed by 10-15 hours of age but complete physical closure doesn’t occur for ≥3 weeks.
What physical exam findings in a neonate would indicate the presence of a patent ductus arteriosus?
Bounding peripheral pulses, a prominent apical impulse, a systolic thrill noted best in the 2nd intercostal space, and a continuous, machinery-like murmur.
What effect does increasing altitude have on the incidence of patent ductus arteriosus?
There is an increased incidence of PDA in infants born above altitudes of 3,000 feet.
What deficiency underlies the the pathophysiology of RDS in premature infants?
Surfactant deficiency. If there is insufficient surfactant, air spaces collapse near end-expiration.
In utero, where does all the fetal glucose come from?
The fetus receives all its glucose from transplacental passage, as under normal conditions it does not synthesize its own glucose. In the 3rd trimester, fetal glucose levels are ~80% of maternal levels.
Why are premature infants at higher risk for developing hypoglycemia in the neonatal period compared with full term infants?
Hepatic glycogen stores begin to increase significantly only toward the end of the 3rd trimester.
At term, what percent of the body is water? What is the relative percentage of intracellular vs extracellular water?
At term, infants are made up of 75-80% water, 2/3 of which is intracellular and 1/3 extracellular.
What is responsible for most of an infant’s weight loss in the first week of life?
During the first week of life, water loss accounts for much of an infant’s weight loss. Most of this water loss is intracellular and interstitial.
